1. Technical Field
The present invention relates to technology for detecting failure on a network.
2. Description of the Related Art
When two communication devices (layer 2 switches, for example) are mutually connected via a network, two paths (communication paths) are established in both directions between the two communication devices. When a failure occurs with one path (called a “unidirectional path failure”), various problems occur on the network such as looping of the frame. Therefore, in order to detect unidirectional path failure, a UDLD (Uni-Directional Link Detection) protocol is proposed.
With UDLD, each communication device sends a link health-check packet to the other communication device, and detects whether a unidirectional link failure occurs based on whether a link health-check packet sent from the other communication device is received.
With UDLD, analysis of various parameters included in the received packet is performed using software, and detection of whether the unidirectional path failure occurs is performed based on those analysis results. Therefore, there is a problem that long time is required until failure detection. Accordingly, shortening of the unidirectional path failure detection time is desired.
Taking into consideration at least part of the problems described above, the problem the present invention attempts to address is to detect unidirectional path failure between communication devices in a short time.